Cellular communications systems continue to grow in popularity and have become an integral part of both personal and business communications. Cellular phones allow users to place and receive voice calls most anywhere they travel. Moreover, as cellular telephone technology has increased, so too has the functionality of cellular devices. For example, many cellular devices now incorporate personal digital assistant (PDA) features such as calendars, address books, task lists, etc. Moreover, such multi-function devices may also allow users to wirelessly access electronic mail (email) messages and the Internet via a cellular network.
Many such devices operate in an always-on, always-connected mode, in that they are continuously trying to maintain service from the wireless network. However, this can lead to problems in that if a cellular base station is administratively closed or otherwise unable to establish a wireless communications link with such a device, then the device may quickly run its battery down trying to continually establish the link. This may similarly occur if the cellular device cannot establish a link because it is out of range of the base station, for example. In addition to the battery drain, in some circumstances this may result in wasted network resources as well.
Various approaches have been used in the prior art to address this problem. By way of example, U.S. Pat. No. 5,794,146 is directed to a method for conserving battery power in a mobile station searching to select a serving cell. The mobile station varies the interval between scans for the beacon signals of cells in a communications system to save battery power when the mobile station is searching to select a serving cell. The interval between scans is increased in response to the time elapsed since the start of the search. Initially, the scans are conducted with a small interval therebetween in the hope of quickly acquiring a serving cell. If a serving cell is not selected during this initial period of time, then the interval between scans is calculated to increase in response to the increase in elapsed time since the start of the search. If a serving cell is not selected during this period of calculated intervals, then the interval is set to a maximum limit to save battery power. The interval between scans may also be changed based upon the quantity and signal strength of beacon signals provided by neighboring serving cells (i.e., base stations).
Despite the presence of such prior art systems, additional flexibility may be desired in some applications for varying scan rates for accessing a cellular base station to save battery power and reduce waste of network resources.